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Fetal hemoglobin induction with a DNMT1 inhibitor
In order to further assess the effect of GSK3482364 on alternative dose schedules, SCD mice were dosed as previ- ously described or on a reduced frequency schedule (b.i.d for 3 weekdays). Induction of HbF was observed to be approximately equivalent for mice dosed on both sched- ules (Online Supplemental Figure S3A). Since both dose regi- mens were equally efficacious, we next tested the effect of dosing GSK3482364 on the reduced frequency schedule for either 2 or 4 weeks to determine the effect of longer dose duration on efficacy and tolerability. Both 2- and 4- week dosing regimens were well-tolerated with no effects on body weight compared to control mice, and all mice
exhibited significant gain in HbF (Online Supplemental Figure S3B). Following 4 weeks of dosing, there was a small increase in percentage HbF induction compared to animals dosed for only 2 weeks, but this increase was not found to be significant. As with previous studies, periph- eral blood cell counts measured after 4 weeks indicated no remarkable differences from vehicle treated animals in any parameters. These results demonstrate that GSK3482364 can robustly induce HbF in vivo with inter- mittent dosing, and that it is well-tolerated for up to 4 weeks without causing evidence of myelosuppression in mice.
AB
Figure 5. Effects of GSK3482364 and decitabine in vivo. (A) Bars represent mean percentage fetal hemoglobin (%HbF) +/- standard deviation (SD), measured by high-performance liquid chromatography (HPLC), in whole blood of sickle cell mice treated with GSK3482364 (twice daily [p.o.]) or decitabine (thrice weekly [s.c.]) for 12 days. Red circles represent mean +/- SD of DNA methylation (-53bp HBG1 methylcytosine) from bone marrow of 4-6 mice. (B) Bone marrow was further eval- uated for HBG1, HBA, and HBB mRNA levels by reverse transcriptase quantitative polymerase chain reaction. In all cases levels are normalized to vehicle-treated control levels. Asterisks indicate significance by 1-way ANOVA (*P<0.01; **P<0.001).
Figure 6. Effects of GSK3482364 on bone marrow cellularity. Representative histopathology images (15x) of sternum bone marrow for mice following 12 days
dosing with
GSK3482364. b.i.d.: twice daily; p.o.: orally.
vehicle or
haematologica | 2021; 106(7)
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